* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

ul,
ol {
  list-style: none;
}

a {
  text-decoration: none;
}

input,
button {
  border: none;
  outline: none;
}

.fl {
  float: left;
}

.fr {
  float: right;
}

/* 清除浮动 */
.clearfix::after {
  content: '.';
  display: block;
  clear: both;
  height: 0;
  visibility: hidden;
}

/* 兼容ie6 ie7 */
.clearfix {
  *zoom: 1;
}

body {
  background-color: #f3f5f7;
  /* height: 3000px; */
}

/* 版心 */
.w {
  width: 1200px;
  margin: 0 auto;
}

/* header*/
.header {
  height: 42px;
  /* background-color: pink; */
  margin: 30px auto;
}

/* logo */
.logo {
  width: 195px;
  height: 42px;
  /* background-color: red; */
}

.logo h1 {
  width: 100%;
  height: 100%;
}

.logo h1 a {
  display: block;
  width: 195px;
  height: 42px;
  background: url(../images/logo.png);
  /* 京东的做法 */
  font-size: 0;
}

/* nav */
.nav {
  height: 42px;
  margin-left: 70px;
}

.nav ul li {
  float: left;
  margin-right: 26px;
}

.nav ul li a {
  display: block;
  height: 42px;
  padding: 0 9px;
  line-height: 42px;
  font-size: 18px;
  color: #050505;
}

.nav li a:hover {
  border-bottom: 2px solid #00a4ff;
}

/*  search*/
.search {
  width: 412px;
  height: 40px;
  margin-left: 59px;
  /* background-color: blue; */
}

.search input {
  width: 360px;
  height: 40px;
  border: 1px solid #00a4ff;
  padding-left: 17px;
  border-right: 0;
  font-size: 14px;
}

/*  input::placeholder*/
input::placeholder {
  color: #bfbfbf;
}

.search button {
  width: 50px;
  height: 40px;
  background-color: pink;
  background: url(../images/btn.png);
}

/* user */
.user {
  margin-left: 30px;
  height: 42px;
  line-height: 42px;
}

.user img {
  /* CSS提高讲解详细原理 */
  vertical-align: middle;
}

/*  banner*/
.banner {
  height: 420px;
  background-color: #1c036c;
}

.banner .w {
  height: 420px;
  background-color: pink;
  background: url(../images/banner2.png) center top;
}

.aside {
  width: 190px;
  height: 420px;
  background-color: rgba(0, 0, 0, .3);
}

.aside ul li {
  height: 44px;
  line-height: 44px;
  padding: 0 20px;
}

.aside ul li a {
  font-size: 14px;
  color: #fff;
}

.aside ul li a:hover {
  color: #00b4ff;
}

.aside ul li a::after {
  float: right;
  content: ">";
}

/* 课程 */
.course {
  /* 浮动的盒子不会嵌套块级元素塌陷问题 */
  margin-top: 50px;
  width: 228px;
  height: 300px;
  background-color: #fff;
}

.course .title {
  height: 48px;
  background-color: #9bceea;
  text-align: center;
  line-height: 48px;
  font-size: 18px;
  color: #fff;
}

.course .content {
  padding: 0 19px;
}

.content dl {
  padding: 12px 0;
  border-bottom: 2px solid #e5e5e5;
}

.content dl dt {
  font-size: 16px;
  color: #4e4e4e;
}

.content dt span {
  font-size: 14px;
}

.content dl dd {
  font-size: 12px;
  color: #a5a5a5;
}

/* 全部课程 */
.more {
  display: block;
  width: 200px;
  height: 41px;
  border: 1px solid #00a4ff;
  margin: 4px auto 0;
  /* background-color: pink; */
  text-align: center;
  line-height: 41px;
  font-size: 16px;
  font-weight: 700;
  color: #00a4ff;
}

/* goods */
.goods {
  height: 60px;
  margin-top: 8px;
  background-color: #fff;
  /* 继承 */
  line-height: 60px;
  /* CSS高级讲解 */
  box-shadow: 0px 2px 3px 0px rgba(118, 118, 118, 0.2);
}

.goods ul li {
  float: left;
}

.goods ul li a {
  border-right: solid 1px #bfbfbf;
  padding: 0 30px;
  font-size: 16px;
  color: #050505;
}

.goods ul li a:hover {
  color: #00a4ff;
}

.goods ul li:last-child a {
  border-right: 0;
}

.goods .mod {
  padding-right: 26px;
  font-size: 14px;
  color: #00a4ff;
}

/* 精品推荐大模块  */
.box {
  margin-top: 35px;
}

.box-hd {
  height: 40px;
  /* background-color: orange; */
}

.box-hd h3 {
  height: 40px;
  font-size: 20px;
  color: #494949;
  font-weight: 400;
}

.box-hd a {
  margin: 8px 30px 0 0;
  font-size: 12px;
  color: #a5a5a5;
}

.box-bd li {
  float: left;
  width: 228px;
  height: 270px;
  background-color: #fff;
  margin-right: 15px;
  margin-bottom: 15px;
}

.box-bd li:nth-child(5n) {
  margin-right: 0;
}

.box-bd .pic {
  width: 100%;
}

.box-bd li h4 {
  height: 50px;
  margin: 25px 20px 0 24px;
  font-size: 14px;
  color: #050505;
  font-weight: 400;
}

.box-bd li p {
  margin-left: 23px;
  font-size: 12px;
  color: #999999;
}

.box-bd li p span {
  color: #ff7c2d;
}

.box-bd li a {
  display: block;
  width: 228px;
  height: 270px;
}

/* footer */
.footer {
  padding-top: 30px;
  height: 417px;
  background-color: #fff;
}

.footer .left p {
  margin: 25px 0 15px 0;
  font-size: 12px;
  color: #666666;
}

.app {
  display: block;
  width: 120px;
  height: 36px;
  border: solid 1px #00a4ff;
  text-align: center;
  line-height: 36px;
  color: #00a4ff;
  font-size: 16px;
}

.footer .right dl {
  float: left;
  margin-left: 120px;
}

.right dl dt {
  margin-bottom: 15px;
  font-size: 16px;
  color: #333;
}

.right dl dd a {
  font-size: 12px;
  color: #333;
}